Looks like your dataset is empty. We don't know what your dataset contains, so here an example with the built-in iris
dataset. First a proper plot, using the same geoms and mappings you use:
library(ggplot2)
ggplot(iris, aes(y = Sepal.Length, x = Sepal.Width)) +
geom_jitter(aes(col = Species)) +
geom_smooth(method = "lm", se = FALSE, col = "black")

Now I remove all the data from the dataset and replot:
library(dplyr)
iris_empty <- filter(iris, Sepal.Length < 0)
ggplot(iris_empty, aes(y = Sepal.Length, x = Sepal.Width)) +
geom_jitter(aes(col = Species)) +
geom_smooth(method = "lm", se = FALSE, col = "black")

A simple head(Wc)
would confirm whether your dataset actually contains any data.